Recently, phase change memories (Patent Literature 1, 2) using chalcogenide materials as storage materials have been actively studied. A memory structure of the phase change memory is a structure in which the recording material is sandwiched by metal electrodes. The phase change memory is a variable resistance type memory that memorizes information by using a phenomenon in which the recording material between the electrodes has different resistance states.
The phase change memory memorizes information by using a phenomenon in which resistivities of the phase change materials such as Ge2Sb2Te5 are different in an amorphous state and a crystal state. The phase change memory has higher resistance in the amorphous state and has lower resistance in the crystal state. Therefore, read is performed by biasing voltage difference across an element, measuring current flown through the element and determining whether the resistance state of the element is high or low.
The phase change memory performs data programing/erasing by changing electric resistance of a phase change film in different states by Joule heat generated by current. A reset operation, in other words, an operation to change into the amorphous state being high resistance is performed by melting the phase change material by biasing large current for a short time, and thereafter by quenching by rapid decrease in the current. On the other hand, a set operation, in other words, an operation to change into the crystal state being low resistance is performed by biasing sufficient current to maintain crystallization temperature of the phase change material for a long period. This phase change memory is suitable for reduction of memory cell size in principle because, when the reduction of memory cell size of the phase change memory proceeds, required current to change a state of a phase change film becomes lower. Therefore, the phase change memory has been actively studied.
As a method for integrating the memory using these variable resistance type elements, Patent Literature 1 discloses constitution in which, in stacked structure formed by alternately stacking a plurality of gate electrode materials and insulator films, a plurality of through holes that pass through the entire layers is collectively patterned, and a gate insulator film, a channel layer, and a phase change film are formed and patterned on the inside of the through holes.